Television antenna



TELEVISION ANTENNA Filed Fb. 23, 1959 Inventor: HenTH P. Thomas,

b HM MMAM His ttoPT eytransmission lines.

Patented Aug. 27, 1940 TELEVISION v ANTENNA '7 Henry P. Thomas,Schenectady, N. Y., assignor to General-Electric. Company, a corporationof New York Application February 23, 1939, Serial No.257,8s 6 Claims.(01. 250-33) I My invention relates to antennas for radio transmitters,and particularly for transmitters designed for the transmission o'farelatively Wide band of ultra high frequencyoscillations, such asemployed in 'tel'e'visionj q It is an object of my invention to providean improved television. antenna system which radiates horizontallypolarized waves having a substantially circular fieldjpattern in thehorizontal plane. p

It isa further object ofmy invention to provide an antenna system*fortelevision wherein high angle radiations is reduced and the effectivetransmitted field strength in the horizontal plane over the circularfield patternfis increased.

It is another object to provide an antenna systen for television whereinthe effective transmitted field strength is increased without incur ringdistortion" of the radiation pattern whenv easily provided to preventstanding waves in the In accordance with" the present invention the Iforegoingand other objects are attained by the provision of an antennacomprising eight radiators or conductors defining a cubical space, theconductors being arranged 'to form two horiof the squares from anoscillation source and in such manner that no distortion occurs in anycQmponentof the'band of oscillationswhich is transmitted. r p

, ,The novel features which I believe to be characteristic of myinvention are set forth with particularity in the appended claims. Myinvention itself, however, both as to its organization and methodofoperation together with further objects the single figure of whichillustrates partially diagrammaticallya radio transmission systemembodying my invention. In the drawing the numerals I and 2 designaterespectively an antenna arranged in accordance with my invention and atransmitter for supplying oscillations thereto, the transmitter, whichmay be of kilowattpower, being arranged,-for example, .to supplyoscillations for" television transmission in the four and one half meterband. The band width may be ofthe usual order, of five megacycle'a'forexample;

conductorsi to lo arranged to form two iden tical squares [I and 12 openat the corners, one square directly above the other and the squaresspaced apart a distance equal approximately to the length of one of theconductors or'to the length of one side of the squares. The conductors 3.to in are preferably constituted by hollow bars of conductive material,such as copper, which in the present embodiment may be four inches inoutside diameter and approximately one half wave length of thetransmitted Wave in length, in the present instance approximately sevenfeet.

To supply the antenna from the source,2, adjacent pairs of conductors 3and 4 and 5 and 6 of one square H are connected respectively at thecorners l3 and I4 thereof to the corresponding pairs of conductors l andB and 9 and ill of the other square l2 at the corners l5 and It thereof.For this purpose a pair of leads l! are connected respectively betweenthe extremities of the par- 'allel conductors 3 and I and between theextremities'of the parallel conductors 5 and 9,*'and' a pair of leads ii?are connected between the extremities of the parallel conductors e and 8and between the extremities of the parallel conductors t and iii. Apairof bridging leads l9 and connect respectively the midpoints 2i and22-of the pairs of leads l1 and I8, and a pair Inf of concentric lines23 and M constituting a transmission line 25 connect respectively themidpoints 26 and 2? of the bridging leads l3 and 20 to the oscillationsource 2.

The transmission means between source 2 and tion of the bridging leadsl9 and 2B, and the transmission line 29 formed by a half section of theleads I! and 18. To prevent standinggwaves in this transmission meansthe two adjacent convductors, 3 and 4 in the present case, and thetransmission line'sections 29, 28 and 25are so dimensioned and arrangedthat the impedance of the two adjacent conductors, 3 aud t, equals thesurge impedance of section 29, the impedance of section 28 is equal toone half the impedance of section 29, and the impedance of transmissionline 25 1s equal to one half theimpedance of section 2 8. The sameconstants hold for the transmission means from source 2 to the othercorners l4, l5 and IS, the impedance in general being the same for thetransmission means connecting source 2 to each of thepairs of conductors3and 4, 5 and 6,1 and 8, and Sand 10. I Y

In operation of the transmission "system illustratedin the drawing, theWide band of television frequencies being impressed, at'opposite corners.l3 and I4, and l5 and lBpon the'horizontal squares H and I2,currentsfiow in the antenna- The antenna I comprises eight radiators orwhich are of like phase in all of the conductors 3 to ID, as indicatedby the arrows. Since the conductors in the horizontal squares areexcited cophasally, the radiated energy is horizontally polarized'andthe horizontal field pattern is of approximately circular'form. Sincethe twoi dentical horizontal squares I! and I2 are spaced verticallyapproximately a half wave length'of the transmitted oscillations, thesubstantially circular horizontal beam from the antenna is substantiallyflattened, the'eii'ective strength of of saidvertical leads extendingbetween said two the ground signal being therefore substantiallyincreased over that of the ground signal which would be provided by asingle square.

In the embodiment of the invention illustrated tion. It is to beunderstood, however, that the invention is susceptible of variouschanges and modifications and that by the appended claims I intend tocover any such modifications as fall within the true spirit and scope ofmy invention; What I claim as new and desire to secure-by Letters Patentof the United States is:

1. In a transmission system comprising a source of oscillations, anantenna comprising eight cone ductors arranged to form two horizontalsquares open at the corners and one directly abovethe other, the lengthof saidconductors and the 'distance between said squares beingapproximately equal to a half: wave length of said oscillations, twopairs of vertical leads connectingrespe'ctlvely at two opposite cornersof said squares the extremities of opposite conductors of one square. tothe extremities ofthe corresponding opposite conductors of the othersquare, and means to connect one terminal of said source to the midpoints of one of said pairs and to connect the other terminal of saidsource to the midpoints of the other pair. I

2. In a transmission system comprising a source of oscillations, anantenna comprising a set of four conductors arranged to form ahorizontal square open at the corners, a second set of four conductorsarranged to form a second horizontal square open at the corners directlyabove said first square and spaced therefrom a distance approximatelyequal to a side of said squares, two pairs of. vertical leads,connecting respectively at two opposite corners of said squares theextremities of opposite conductors of one square to the extremities ofthe corresponding opposite conductors of the other square, a pair ofleads bridging respectively the midpoints of said pairs L of verticalleadspand means to'connect the opposite terminals of saidsourcerespectively to the midpoints of said bridging leads,

3 In atransmission system comprising an os-. cillation source, anantenna comprising two sets of conductors, each sethaving fourconductors arranged in a square open at the corners, said squares beingequal and spaced apartone above the other a distance approximately equalto the length of one of saidconductorstwo pairs ofvertical leadsconnecting respectively at two opposite corners of said squares theextremities of opposite conductors of one square to the extremities ofthe correspondingiopposite conductors of theother square, and means toconnect the terminals of said source respectively to the midpoints ofsaid pairs, said conductors and said vertical leads being so arrangedthat the impedance of any given adjacent two of said conductorsconnected to the corresponding section conductors and said connectingmeans is equal to the surge impedance of said section.

4. In a transmissionsystem comprising a source of oscillations, anantenna comp-rising eight conductors arranged to form two horizontalsquares spaced apart a distance approximately equal to aside of saidsquares,.two pairs of vertical leads connecting respectively oppositeconductors oi one square to the corresponding opposite conductors of theother squarejleads bridging the midpoints of said pair of verticalleads, and a transmission line connecting said source to the midpointsof said bridging leads, said conductors, vertical leads, bridging leadsand transmission line being so arranged that the impedance of any giventwo of said conductors connected to the corresponding section of saidvertical leads is equal to the surge impedance of said section, theimpedance of that section of said bridging leads between the connectionpoint thereto of said ing spaced apart a distance approximately equal toa side of said squares, means to supply current from said source to saidconductors at two opposite corners of one square and at two oppositecorners of the-other squaredirectly, above said first-named corners,said means being so arranged that the current in all of said conductorsis of like phase,. said means comprising connection-means between saidsource and said "four corners so arranged that the impedance of saidconnectionmeans is the same between said source and, each of saidcorners. I

6. Ina transmission'system comprising a source of oscillations, anantenna comprising eight identical conductorsarrangedto form twohorizontal squares open v at the corners, one square being directlyabove the other and the squares being spaced apart a distanceapproximately equal. to aside of said squares, means to. sup-plycurrent-from said source to said squares at op-' posite corners thereoiso arranged that the currents in all of said conductors are .of likephase,

saidmeans comprising two identical transmission lines each constitutedby .two identical sections,

said lines connecting respectively the two oppoa site corners of onesquare to the two corresponding opposite corners of the;-','otl1ersquare, means to, connect the connection point of .thesections of one ofsaid lines to said source, and means having-the same impedance as saidlast-named means to connect the connection point of the sections of theother line tosaid source;

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